In the dozing operation of a known bulldozer, the operator manually manipulates the blade to be raised, lowered, tilted or pitched in order to regulate the load on the blade caused by ground-working and earth moving while avoiding the traveling slip (shoe slip) of the vehicle body. During the operation, a shift, for example, from digging to carrying, is based on the volume of earth accumulated on the front face of the blade (i.e., earthwork) that has been estimated by the operator's perception from the shoe slip condition of the vehicle body or the soil spilt from the blade surface.
However, it is difficult for the operator to accurately estimate the blade's earthwork by his perception, particularly when the bulldozer has a large-sized blade and causes little shoe slip, so that a smooth shift from digging to carrying cannot be carried out with effective timing. In addition, not only does the operation involving estimation based on human perception cause great fatigue to an unskilled operator but also such estimation itself is very difficult.
The present invention has been made with the purpose of overcoming the above problem and one of the objects of the invention is therefore to provide a dozing system for a bulldozer that is capable of automatically detecting the volume of earth accumulated on the front face of the blade during a dozing operation without depending on the operator's perception.
Another object of the invention is to provide a dozing system capable of automatically switching from digging to carrying according to the automatic detection of the volume of earth accumulated on the face of the blade.